Material vendors who also host rich training and knowledgebase educational sites and tools. These vendors often will show how to build useful things with the componenets / materials they sell.
Vendors of electronic compomponents
Includes vendors of build materials
Documentation resources for the Arduino platform
Software development tools such as IDEs, CAD and and other tools.
Websites that teach core fundamentals in electrical and mechanical design and engineering.
Assorted sites that inspire creativity and demonstrate concepts.
Other area groups with a Maker purpose.